https://www.gentoo.org/get-involved/mailing-lists/ The 'subscribe' URLs are alike: gentoo-user+subscribe@lists.gentoo.org However, '+' stands for space in urlencode, so (some?) mail clients get a space there instead. We should probably use %2B instead.
Sorry, I meant: mailto:gentoo-user+subscribe@lists.gentoo.org (and it would be changed to: mailto:gentoo-user%2Bsubscribe@lists.gentoo.org )
> Summary: Mailing list subscription URL malformed Malformed, no. RFC 6068 makes it optional: "'+' characters MAY be encoded as %2B." I've done it for the few list links where it didn't take a lot of effort. I won't go to great lengths to set this encoding domain wide though.